1. Field of the Invention
This invention relates generally to wireless communication networks and, more particularly, to a method and apparatus for determining a mobile user""s location within a wireless communication network.
2. Description of the Related Art
Wireless communication networks, such as radio communication networks, have become increasingly popular over the years due in part to the freedom of movement they provide to the communicating public. As a result of this popularity, wireless communication networks have rapidly expanded into several new coverage areas, thereby increasing the range of their wireless coverage to the mobile user.
Typically, it is desirable to determine the geographical location of a mobile user within a wireless communication network in such instances as a 911 emergency call, for example. In landline communication networks, the location of the user""s communication equipment is stationary, and, thus, the location of the communication equipment may be easily determined by the telephone number of the user""s equipment that is cross-referenced to a static location (i.e., an address). In wireless communication networks, however, the mobile user""s location may change frequently, thereby making it much more difficult to ascertain the user""s precise geographical location within the wireless network. Moreover, as these wireless communication networks expand their communication coverage, it becomes more difficult to determine a precise geographical location of a mobile user since there is a much larger area in which the mobile user may communicate.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
One aspect of the present invention is seen in a method for determining a location of a mobile station within a wireless communication network. The wireless communication network includes a plurality of base receivers coupled to a switch for receiving communication from the mobile station during a specified period of time. A signal is transmitted from the mobile station for receipt by at least two of the base receivers. A timing error, associated with the transmitted signal, is determined for each of the base receivers that received the transmitted signal. A determination is made of the separation distance between the mobile station and each base receiver that received the transmitted signal based at least upon the timing error, and a determination is made of the location of the mobile station within the wireless communication network based upon the separation distance between the mobile station and the base receivers that received the transmitted signal.
Another aspect of the present invention is seen in a wireless communication system for determining a location of a mobile station communicating therein. The system comprises a plurality of base receivers for receiving wireless communication, a controller, and at least one mobile station for transmitting a signal for receipt by at least two of the base receivers. The base receivers that received the transmitted signal determine a timing error associated with the transmitted signal, and the controller determines a separation distance between the mobile station and each base receiver that received the transmitted signal based at least upon the timing error. The controller further determines the location of the mobile station within the wireless communication network based upon the separation distance between the mobile station and the base receivers that received the transmitted signal.